Rotorcraft and connecting structure for arm and airframe of rotorcraft

ABSTRACT

A rotorcraft and a connecting structure for an arm and an airframe of a rotorcraft are provided. The connecting structure includes: a fixed sleeve pipe configured to extend out from a circumferential edge of the airframe; an insertion head configured to be disposed to the first end of the arm and configured to be inserted into the fixed sleeve pipe; a lock sleeve configured to be fitted over the arm and having an insertion portion configured to be embedded into the insertion groove; and a lock nut configured to be fitted over the arm and configured for being in threaded connection with the fixed sleeve pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International PatentApplication No. PCT/CN2015/091753, filed Oct. 12, 2015, which claims thebenefit of prior Chinese Applications No. 201420626211.1 filed Oct. 27,2014, No. 201420631048.8 filed Oct. 27, 2014 and No. 201420631071.7filed Oct. 27, 2014. The entire contents of the above-mentioned patentapplications are incorporated by reference as part of the disclosure ofthis U.S. application.

FIELD

The present disclosure relates to a field of aircraft, specifically to arotorcraft and a connecting structure for an arm and an airframe of therotorcraft.

BACKGROUND

A rotorcraft is also called a rotor helicopter, which usually includesan airframe, an arm and a propeller. An end of the arm is connected withthe airframe, and the propeller is mounted to the other end of the arm.

The arm and the airframe of a traditional rotorcraft are connected in anintegrated manner, and the airframe and other arms are scrapped if onearm is bent if the rotorcraft falls down.

SUMMARY

A rotorcraft and a connecting structure for an arm and an airframe ofthe rotorcraft are provided in the embodiments of present disclosure.

In one aspect, a connecting structure for an arm and an airframe of arotorcraft includes: a fixed sleeve pipe configured to extend out from acircumferential edge of the airframe; an insertion head configured to bedisposed to a first end of the arm and configured to be inserted intothe fixed sleeve pipe, in which the insertion head is provided with aprotrusion portion protruding from an outer surface of the arm, and aninsertion groove is formed between the protrusion portion and the outersurface of the arm; a lock sleeve configured to be fitted over the armand having an insertion portion configured to be embedded into theinsertion groove, in which the insertion portion and the protrusionportion are configured to be in threaded connection; and a lock nutconfigured to be fitted over the arm and configured for being inthreaded connection with the fixed sleeve pipe, in which a second end ofthe lock nut has a tensing end configured for abutting against a secondend face of the protrusion portion.

In an embodiment, the insertion head is fitted over the front end of thearm in a detachable manner.

In an embodiment, the fixed sleeve pipe is provided with a female plugtherein, and the insertion head is provided with a male plug insertedinto the female plug.

In an embodiment, the insertion head is provided with an extensionportion extending outwards in a radial direction of the insertion head,the protrusion portion is formed by means of an edge of the extensionportion extending towards the rear end of the arm, and the fittingsurface is a front end surface of the extension portion.

In an embodiment, a surface of the insertion head is provided with agroove extending in an axial direction of the insertion head, and aninner wall of the fixed sleeve pipe is provided with a boss embeddedinto the groove.

In another aspect, the present disclosure further provides a rotorcraftincluding: an arm, an airframe and a connecting structure for the armand the airframe, in which the connecting structure comprises: a fixedsleeve pipe configured to extend out from a circumferential edge of theairframe; an insertion head configured to be disposed to a first end ofthe arm and configured to be inserted into the fixed sleeve pipe, inwhich the insertion head is provided with a protrusion portionprotruding from an outer surface of the arm, and an insertion groove isformed between the protrusion portion and the outer surface of the arm;a lock sleeve configured to be fitted over the arm and having aninsertion portion configured to be embedded into the insertion groove,in which the insertion portion and the protrusion portion are configuredto be in threaded connection; and a lock nut configured to be fittedover the arm and configured for being in threaded connection with thefixed sleeve pipe, in which a second end of the lock nut has a tensingend configured for abutting against a second end face of the protrusionportion.

Additional aspects and advantages of the present disclosure will begiven in part in the following descriptions, become apparent in partfrom the following descriptions, or be learned from the practice of thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of the present disclosure willbecome apparent and more readily appreciated from the followingdescriptions made with reference to the drawings, in which:

FIG. 1 is a schematic view of a rotorcraft according to an embodiment ofthe present disclosure;

FIG. 2 is an exploded view of a heat dissipation structure for a motorof a rotorcraft according to an embodiment of the present disclosure;

FIG. 3 is a section view of the heat dissipation structure for the motorshown in FIG. 2;

FIG. 4 is a schematic view of a head cover of the heat dissipationstructure for the motor shown in FIG. 2;

FIG. 5 is a schematic view of a connecting structure for an arm and anairframe of a rotorcraft according to an embodiment of the presentdisclosure;

FIG. 6 is a section view of the connecting structure for the arm and theairframe shown in FIG. 5;

FIG. 7 is an enlarged view of portion A shown in FIG. 6;

FIG. 8 is a schematic view of an assembly and disassembly structure fora foot stand of a rotorcraft according to an embodiment of the presentdisclosure;

FIG. 9 is a schematic view of the foot stand according to the assemblyand disassembly structure for the foot stand in assembly shown in FIG.8;

FIG. 10 is a sectionally schematic view of the foot stand according tothe assembly and disassembly structure for the foot stand in disassemblyshown in FIG. 8.

REFERENCE NUMERALS

rotorcraft 1000;

airframe 100; fixed sleeve pipe 11; a first external thread 111; boss112; accommodating groove 12; top wall 121; hole 122; clamping slot 123;

arm 200; first end 201 of arm 200; second end 202 of arm 200; lock nut21; lock sleeve 22; insertion portion 221; a second external thread 222;insertion head 23; fitting surface 231; protrusion portion 232; internalthread 233; extension portion 234; groove 235; first seal ring 24;second seal ring 25; flange 26;

propeller 300;

heat dissipation structure 400 for motor; casing 410; air inlet 411; airchannel 412; head cover 430; air flow pick 431; water guiding surface432; support 440; mounting stand 450;

foot stand 500; fixing stand 51; fixing groove 511; position limitinggroove 512; insert 52; plug pin 53; stop piece 531; pushrod 54; elasticcomponent 55; connecting stand 56;

motor 600.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described in detail in thefollowing. Examples of the embodiments are shown in the drawings, andthe same or similar elements and the elements having same or similarfunctions are denoted by like reference numerals throughout thedescriptions. The embodiments described with reference to the drawingsare illustrative, which is only used to explain the present disclosureand shouldn't be construed to limit the present disclosure.

In the specification, it should be understood that terms such as “axialdirection”, “circumferential direction”, “up”, “down”,“front”, “rear”,“left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”,“outer” should be construed to refer to the orientation as thendescribed or as shown in the drawings under discussion. These relativeterms are for convenience of description and do not require that thepresent disclosure be constructed or operated in a particularorientation, so shall not be construed to limit the present disclosure.In addition, terms such as “first” and “second” are used herein forpurposes of description and are not intended to indicate or implyrelative importance or significance or to imply the number of indicatedtechnical features. Thus, the feature defined with “first” and “second”may comprise one or more of this feature. In the description of thepresent invention, “a plurality of” means two or more than two, unlessspecified otherwise.

In the present invention, it should be noted that, unless specified orlimited otherwise, the terms “mounted,” “connected,” “coupled,” shouldbe understood broadly, and may be, for example, fixed connections,detachable connections, or integral connections; may also be mechanicalor electrical connections; may also be direct connections or indirectconnections via intervening structures; may also be inner communicationsor interaction relationships of two elements, which can be understood bythose skilled in the art according to specific situations.

In the present invention, unless specified or limited otherwise, astructure in which a first feature is “on” or “below” a second featuremay include an embodiment in which the first feature is in directcontact with the second feature, and may also include an embodiment inwhich the first feature and the second feature are not in direct contactwith each other, but are contacted via an additional feature formedtherebetween. Furthermore, a first feature “on,” “above,” or “on top of”a second feature may include an embodiment in which the first feature isright or obliquely “on,” “above,” or “on top of” the second feature, orjust means that the first feature is at a height higher than that of thesecond feature; while a first feature “below,” “under,” or “on bottomof” a second feature may include an embodiment in which the firstfeature is right or obliquely “below,” “under,” or “on bottom of” thesecond feature, or just means that the first feature is at a heightlower than that of the second feature.

A rotorcraft 1000 according to embodiments of the present disclosurewill be described with reference to FIG. 1 to FIG. 10. As shown in FIG.1, the rotorcraft 1000 according to embodiments of the presentdisclosure includes: an airframe 100, an arm 200 and a propeller 300.

A foot stand 500 may be disposed on a bottom of the airframe 100, thefoot stand 500 performs a support function to the airframe 100 and ashock absorption function when the rotorcraft 1000 lands. As shown inFIG. 1, in an embodiment, a plurality of foot stands 500 may be disposedsymmetrically on the bottom of the airframe 100, in an embodiment, onefoot stand 500 may be disposed in a middle of the bottom of the airframe100.

As shown in FIG. 1, a first end 201 (mounting end, root segment, frontend) of the arm 200 is connected onto the airframe 100. As shown in FIG.1, in an embodiment, a plurality of arms 200 such as four, eight or morearms may be provided. The plurality of arms 200 is arrangedsymmetrically with respect to the airframe 100. A second end 202 (freeend, terminal end, rear end) of each arm 200 is provided with acorresponding propeller 300, and the corresponding propeller 300 isdisposed on the arm 200 horizontally.

The propeller 300 is driven to rotate by a motor 600, a plurality ofmotors 600 may be provided, and the number of the motors 600 may be thesame with that of the propellers 300. For example, each propeller 300 isdriven to rotate by one motor 600. In an embodiment, a mounting locationof each motor 600 corresponds with a location of a correspondingpropeller 300. For example, each motor 600 may also be disposed at thesecond end 202 of the corresponding arm 200.

The rotorcraft 1000 according to embodiments of the present disclosurefurther includes a heat dissipation structure 400 for a motor, aconnection structure of the arm 200 and the airframe 100, and a fastdisassembly and assembly structure of the foot stand 500. The specificembodiments of each of the structures above will be illustrated indetail respectively in the following.

The heat dissipation structure 400 for the motor of the rotorcraft 1000according to embodiments of the present disclosure will be described inthe following with reference to FIG. 1 to FIG. 4. The heat dissipationstructure 400 for the motor of the rotorcraft 1000 according toembodiments of the present disclosure includes: a casing 410, a headcover 430 and a mounting stand 450.

As shown in FIG. 1, the casing 410 is disposed to the second end 202 ofeach arm 200, in an embodiment, there may be provided with a fixedconnection or a detachable connection between the casing 410 and thesecond end 202 of each arm 200. The casing 410 is a hollow structurehaving a top opening and an air inlet 411 in a bottom portion thereof. Amotor body of each motor 600 is disposed inside of the casing 410, in anembodiment, the motor body of each motor 600 may be fixedly mounted withrespect to the casing 410. That is, in a normal operation, the motor 600is still with respect to the casing 410, making the motor 600 drive thepropeller 300 stably. In an embodiment, the motor body of the motor 600is detachably mounted with respect to the casing 410. In an embodiment,a revolving shaft of the motor 600 extends upwards and out of the casing410, and an air channel 412 is formed between an edge of the motor bodyof the motor 600 and an inner wall of the casing 410.

In an embodiment, the air inlet 411 may be a small hole arranged in abottom portion of a side wall of the casing 410, a plurality of smallholes may be provided. As shown in FIG. 2, the small hole may be in theshape of any one such as a circle, a long circle, a polygon or anirregular shape, as long as the air outside can enter the air channel412 in the casing 410 from the air inlet 411.

In an embodiment, the top opening of the casing 410 may be formed withan upper end, which is completely open, of the casing 410, or be formedwith a top portion, which is open, of the air channel 412 in the casing410.

The head cover 430 is connected to the revolving shaft of the motor 600synchronously and covers the top opening in the above. A first gapcommunicating the air channel 412 with the outside is formed between alower surface of the head cover 430 and a top end face of the casing410. The first gap is formed between a lower surface of acircumferential edge of the head cover 430 and a top end face of thecasing 410. A communication path is formed among the air inlet 411, theair channel 412 together with the first gap mentioned above and an outerenvironment. The lower surface of the head cover 430 is provided with aplurality of air flow picks 431.

The mounting stand 450 is fixed to an upper surface of the head cover430 and configured to be connected with the propeller 300. In anembodiment, the mounting stand 450 and the propeller 300 can be mountedin any form, such as being connected in thread, being connected withsnap, being connected by welding and etc., thus the propeller 300 isfixed to the mounting stand 450. With the motor 600 driving the headcover 430 to rotate, the head cover 430 further drives the propeller 300to rotate.

In other words, the casing 410 is fixed to an end of each arm 200 of therotorcraft 1000 and is the hollow structure having the top opening andthe air inlet 411 in the bottom portion. The air inlet 411 may be thesmall hole arranged in the bottom portion of the side wall of the casing410, and the plurality of small holes may be provided. The motor body ofthe motor 600 is mounted inside of the casing 410, and the air channel412 is formed between the circumferential edge of the motor body of themotor 600 and the inner wall of the casing 410. The head cover 430 isconnected to the revolving shaft of the motor 600 synchronously and islocated above the casing 410 i.e. covers the top opening in the above.The first gap is formed between the lower surface of the circumferentialedge of the head cover 430 and the top end face of the casing 410 andcommunicates an upper end portion of the air channel 412 with theoutside. Thus, the communication path is formed among the air inlet 411,the air channel 412 together with the first gap mentioned above and theouter environment, and the lower surface of the head cover 430 isprovided with the plurality of air flow picks 431. The mounting stand450 is fixed to the upper surface of the head cover 430, and an externalthread used to fix the propeller 300 and the mounting stand 450 may beprovided on the mounting stand 450 so as to make the revolving shaft ofthe motor 600 drive the propeller 300 to rotate.

When the motor 600 operates, the revolving shaft thereof drives the headcover 430 to rotate, the plurality of air flow picks 431 disposed on thelower surface the head cover 430 stir the air inside of the casing 410to flow. Under a function of a centrifugal force, a negative pressure isformed in the upper portion of the casing 410, and the air flows fromthe bottom up in the air channel 412. Air at a low temperature in theouter environment enters the air channel 412 through the air inlet 411,exchanges heat with the motor body of the motor 600 at a hightemperature to take out the heat, and flows out along the first gapbetween the head cover 430 and the top end face of the casing 410.

The plurality of air flow picks 431 mentioned above are arranged in acircumferential array around a central axis of the head cover 430, andan extension direction of each of the air flow picks 431 is coincidentwith a radial direction of the head cover 430. In an embodiment, each ofthe air flow picks 431 may be triangular in shape, and a distancebetween a top end face and a bottom end face of each of the air flowpicks 431 decreases gradually from the inside out (that means from oneend to another end).

The plurality of air flow picks 431 may also be arranged to be spiral inshape, and an included angle may be formed between the extensiondirection of each of the air flow picks 431 and the radial direction ofthe head cover 430. In conclusion, the distribution of the air flowpicks 431 arranged on the head cover 430 and the shape of each air flowpick 431 are configured to make the air flow picks 431 stir the air inthe casing 410 to flow outside, generating the negative pressure in theupper portion of the casing 410, when the head cover 430 rotates.

In short, no matter how the air flow picks 431 are arranged on the headcover 430 or what shape the air flow picks 431 have, as long as theplurality of air flow picks can stir the air in the casing 410 and makethe air flow outwards to generate the negative pressure in the upperportion of the casing 410 when the head cover 430 rotates.

In an embodiment, a second gap exists between an inner end (i.e. an endof each of the air flow picks 431 adjacent to a center of the head cover430) of each of the air flow picks 431 and a center of the head cover.Thus, a spaced area located in the center of the head cover 430 isdefined and surrounded by the inner ends of the plurality of air flowpicks 431, and the negative pressure can be formed in the spaced areawhen the head cover 430 rotates along with the revolving shaft of themotor 600. The air pressure of the sucked air is lower than that of theair in an interspace between an inner wall of the casing 410 and themotor 600, thus the hot air in the motor enters the negative-pressurearea surrounded by the inner ends of the plurality of air flow picks 431under a function of the air pressure difference and then is exhaustedfrom the air channel 412 at a high speed, playing a role of heatdissipation for the motor.

In an embodiment, the upper surface of the head cover 430 mentionedabove may be provided with a water guiding surface 432, and the waterguiding surface 432 has a height gradually reducing from a center to anedge. A diameter of the head cover 430 is larger than a diameter of thetop portion of the casing 410, that is, the edge of the head cover 430is located outside of the top edge of the casing 410. The rainwaterflows downwards along the water guiding surface 432 and does not enterthe casing 410 from the first gap formed between the head cover 430 andthe top end face of the casing 410.

In an embodiment, the revolving shaft of the motor 600 is provided witha support 440, the head cover 430 and the mounting stand 450 are fixedto the support 440 through a bolt.

A connecting structure for the arm 200 and the airframe 100 of therotorcraft 1000 according to embodiments of the present disclosure willbe described in the following with reference to FIG. 1, FIGS. 5-7.Referring to an example shown in FIG. 1, in the example, the rotorcraft1000 includes four arms 200, and the rotorcraft 1000 having four arms200 will be taken as an example to be described in the following. Theconnecting structure for the arm 200 and the airframe 100 of therotorcraft 1000 according to embodiments of the present disclosureincludes: a fixed sleeve pipe 11, an insertion head 23, a lock sleeve 22and a lock nut 21.

As shown in FIG. 1 and FIG. 5, the fixed sleeve pipe 11 extends out froma circumferential edge of the airframe 100, and four fixed sleeve pipes11 extend out from the circumferential edge of the airframe 100 and aremounted with the four arms 200 respectively. As shown in FIG. 5 and FIG.6, the insertion head 23 is disposed at the first end 201 (an end of thearm 200 adjacent to the airframe 100, a front end) of each arm 200 andconfigured to be inserted into the fixed sleeve pipe 11. Specifically,the insertion head 23 is fitted over the first end 201 of the arm 200 ina direction from the first end 201 to the second end 202 of the arm 200,that is, as shown in FIG. 5 and FIG. 6, the insertion head 23 is fittedover the first end 201 of the arm 200 from front to rear.

The insertion head 23 is provided with a protrusion portion 232protruding from an outer surface of each arm 200, and an insertiongroove is formed between the protrusion portion 232 and the outersurface of the arm 200. As shown in FIG. 5 and FIG. 6, the protrusionportion 232 may be located at a second end (a rear end) of the insertionhead 23, a third gap is defined between the protrusion portion 232 andthe outer surface of the arm 200, and the third gap is formed to be theinsertion groove. As shown in FIG. 5 and FIG. 6, an opening of theinsertion groove faces the rear. The lock sleeve 22 is fitted over thearm 200 and has an insertion portion 221 embedded into the insertiongroove. Specifically, as shown in FIG. 5 and FIG. 6, the insertionportion 221 is located in front of the lock sleeve 22 and is insertedinto the insertion groove forward.

In an embodiment, the insertion head 23 is fitted over the first end 201of the arm 200 in a detachable manner, for example, the insertion head23 may be mounted to the first end 201 of the arm 200 through threadedconnection, or a snap structure.

The insertion portion 221 may be in threaded connection with theprotrusion portion 232. The tightness between the insertion head 23 andthe lock sleeve 22 can be adjusted according to demands.

The lock nut 21 is fitted over the arm 200, and a second end (a rearend) of the lock nut 21 has a tensing end abutting against a second endsurface (a rear end surface) of the protrusion portion 232. The lock nut21 is in threaded connection with the fixed sleeve pipe 11. When theinsertion head 23 is mounted stably to the arm 200, a position of theprotrusion portion 232 relative to the arm 200 is fixed.

Specifically, as shown in FIG. 5, a first external thread 111 is formedon an outer surface of the fixed sleeve pipe 11 and the lock nut 21 isin threaded connection with the first external thread 111. A secondexternal thread 222, in threaded connection with an inner surface of theprotrusion portion 232, is formed on an outer surface of the insertionportion 221, which can achieve the threaded connection between theinsertion portion 221 and the protrusion portion 232.

In an embodiment, as shown in FIG. 5 and FIG. 6, a fitting surface isformed at a first end (the front end) of the protrusion portion 232, anda first seal ring 24 is clamped between an outer end face (the free endface) of the fixed sleeve pipe 11 and the fitting surface 231.Specifically, the first seal ring 24 is fitted over the outer surface ofthe insertion head 23, thus the insertion head 23 is ensured to belocked tightly with the fixed sleeve pipe 11. In an embodiment, theinsertion head 23 is provided with an extension portion 234 extendingoutwards in a radial direction thereof, and the protrusion portion 232extends from an edge of the extension portion 234 and extends towardsthe second end 202 of the arm 200, and the fitting surface 231 can be afirst end face of the extension portion 234.

In an embodiment, a second seal ring 25 is fitted over the lock sleeve22 and is clamped between an outer surface of the lock sleeve 22 and aninner surface of the second end (the rear end) of the lock nut 21.

In other words, as shown in FIG. 1 and FIGS. 5 to 7, the airframe 100 isprovided with the fixed sleeve pipes 11, and the arm 200 is providedwith the insertion head 23, the lock nut 21 and the lock sleeve 22. Thefixed sleeve pipe 11 extends out from the circumferential edge of theairframe 100 and is provided with the first external thread 111 on theouter surface thereof. The fixed sleeve pipe 11 can be fixed in theairframe 100 in a detachable manner, for example, the airframe 100 isdesigned to have an upper housing and an lower housing which arefastened with each other, the fixed sleeve pipe 11 is pre-embedded in asemi-circular groove of the lower housing, and a degree of freedom ofthe fixed sleeve pipe 11 along an axial direction thereof is limited bya position limiting structure, and then the upper housing is fastened tofix the upper housing and the lower housing, thus fixing the fixedsleeve pipe 11 and the airframe 100. In an embodiment, the fixed sleevepipe 11 and the airframe 100 may also be fixed with other structureswhich are well known by people who is skilled in the related art andwill not be described in detail here.

The insertion head 23 mentioned above is fitted over the front end ofthe arm 200 and is provided with the protrusion portion 232 protrudingfrom the outer surface of the arm 200, and the insertion groove isformed between the protrusion portion 232 and the outer surface of thearm 200. The insertion head may be provided with the extension portion234 extending outwards in the radial direction and the protrusionportion 232 extends from the extension portion extending 234 backwards,and the fitting surface 231 in the radial direction is formed in thefront end face of the extension portion 234 and is fitted with the endface of the fixed sleeve pipe 11. The first seal ring 24 located betweenthe fitting surface 231 and the end face of the fixed sleeve pipe 11 issleeved over the insertion head 23. The lock nut 21 and the lock sleeve22 are both fitted over the arm 200, the lock nut 21 is in threadedconnection with the first external thread 111, and the rear end of thelock nut 21 has the tensing end abutting against the rear end face ofthe protrusion portion 232. When the lock nut 21 is screwed, the tensingend in the rear end face thereof can push the insertion head 23 towardsthe fixed sleeve pipe 11 and make the fitting surface 231 and the endface of the fixed sleeve pipe 11 clamp the first seal ring 24. The locksleeve 22 has the insertion portion 221 embedded into the insertiongroove, and the second external thread 222 is formed on the outersurface of the insertion portion 221. An internal thread 233 is providedin the inner surface of the protrusion portion 232 corresponding to thesecond external thread 222. In addition, the second seal ring 25 isfitted over the lock sleeve 22 and is clamped between the outer surfaceof the lock sleeve 22 and the inner surface of the rear end of the locknut 21. A surface of the arm 200 is provided with a flange 26 and theflange 26 is clamped between the extension portion 234 and the front endface of the insertion portion 221.

During the installation, the lock sleeve 22, the lock nut 21 and theinsertion head 23 are fitted over the front end of the arm 200, then theinsertion head 23 is inserted into the fixed sleeve pipe 11, the locksleeve 22 is screwed, and the insertion head 23 and the lock sleeve 22are locked by means of the second external thread 222 and the internalthread 233. That is, the flange 26 is clamped between the extensionportion 234 and the insertion portion 221, and then the lock nut 21 isscrewed to make the fitting surface 231 and the end face of the fixedsleeve pipe 11 clamp the first seal ring 24 ensuring that the insertionhead 23 and the fixed sleeve pipe 11 are locked. When the lock nut 21 isscrewed, the rear end thereof presses the second seal ring 25. Then theassembly of the arm 200 and the airframe 100 is finished. Threadedconnection of the structure mentioned above results the fast disassemblyand assembly of the arm 200 and the airframe 100, and meanwhile, thefirst seal ring 24 and the second seal ring 25 can be pressed in thethread locking manner, which ensures a seal function of the connectionbetween the airframe 100 and the arm 200. In addition, during theprocess of screwing the lock nut 21, the second seal ring 25 can providecertain preload to the lock nut 21 and ensure a connection securitybetween the lock nut 21 and the fixed sleeve pipe 11.

In an embodiment, connection pieces configured to turn on a circuit aredisposed in the fixed sleeve pipe 11 and the insertion head 23respectively. When the arm 200 and the airframe 100 are assembled, theconnection piece in the fixed sleeve pipe 11 and the connection piece inthe insertion head 23 are in contact with each other, and the circuit isturned on. The circuit may be a power supply circuit and/or a controlcircuit of the motor 600 and the propeller 300.

The connection pieces in the fixed sleeve pipe 11 and the insertion head23 can be any structure, as long as the circuit can be turned on whenthe two connection pieces are in contact. For example, metal sheets maybe disposed in the fixed sleeve pipe 11 and the insertion head 23respectively and the purpose of turning on the circuit can be satisfiedwhen the two metal sheet are in contact. In an embodiment, the fixedsleeve pipe 11 is provided with a female plug therein and the insertionhead 23 is provided with a male plug capable of inserting into thefemale plug.

An outer surface of the insertion head 23 is provided with a groove 235extending in an axial direction of the insertion head 23, and an innerwall of the fixed sleeve pipe 11 is provided with a boss 112 capable ofbeing embedded into the groove 235. In an embodiment, the outer surfaceof the insertion head 23 mentioned is provided with the groove 235extending in the axial direction, and the inner wall of the fixed sleevepipe 11 is provided with the boss 112 capable of being embedded into thegroove 235. During the insertion and installation, the boss 112 isembedded into the groove 235, which can guide the installation of thearm 200 and the fixed sleeve pipe 11. Furthermore, a plurality ofgrooves 235 may be provided in different positions in the insertionheads 23 of the arms 200 of the rotorcraft 1000, the fixed sleeve pipes11 corresponding to the arms 200 are provided with bosses 112corresponding to the grooves 235 in different positions.

The arm 200 and the airframe 100 are locked and fixed by means of thelock nut 21 and the lock sleeve 22 in the present disclosure, and theseal ring is pressed in a thread fasten manner.

A fast assembly and disassembly structure of a foot stand 500 of arotorcraft 1000 according to embodiments of the present disclosure willbe described with reference to FIG. 1 and FIGS. 8-10. Referring to theexample shown in FIG. 1, in the example, the rotorcraft 1000 includestwo foot stands 500, and the two foot stands 500 are arranged at thebottom of the airframe 100 symmetrically with respect to a center lineof the airframe 100. Each of the foot stands 500 has two connecting endsfor the airframe 100, and, each connecting end of each of the footstands 500 is provided with the fast assembly and disassembly structureaccording to embodiments of the present disclosure. As shown in FIG. 1and FIGS. 8-10, the fast assembly and disassembly structure of the footstand 500 of the rotorcraft 1000 according to embodiments of the presentdisclosure includes: an accommodating groove 12 disposed in a bottomwall of an airframe 100 and having a downward opening, a fixing stand51, a plug pin 53, an elastic component 55 and a pushrod 54.

As shown in FIG. 8, a top wall 121 of the accommodating groove 12 isprovided with a hole 122, the fixing stand 51 is fixedly connected toeach foot stand 500 and accommodated in the accommodating groove 12, andthe plug pin 53 is movably mounted into the fixing stand 51.Specifically, the plug pin 53 can move in an up-down direction, aportion of the plug pin 53 passing through an upper surface of thefixing stand 51 is provided with an insertion end, and the insertion endmatches the hole 122 and is inserted into the hole 122. Further, a sidewall of the accommodating groove 12 is provided with a clamping slot123, the fixing stand 51 is provided with an insert 52, and the insert52 is fitted into the clamping slot 123. When the insert 52 is fittedinto the clamping slot 123 and the plug pin 53 is inserted into the hole122, the fixing stand 51 is fixed into the accommodating groove 12, thusachieving a purpose of disposing the foot stand 500 to the airframe 100.

Further, the elastic component 55 is configured to provide an elasticstress to push and press the plug pin 53 so that the insertion end isembedded into the hole 122, i.e. the elastic component 55 is configuredto be in a pressed state, by which the plug pin 53 can be pushed andpressed. The pushrod 54 leads the plug pin 53 to move far away from thehole 122 when pressed, so when the foot stand 500 needs to bedisassembled, the pushrod 54 may be pressed so as to disengage the plugpin 53 from the hole 122, and the fixing stand 51 is rotated downwardstaking the insert 52 as a fulcrum so that the insert 52 is disengagedfrom the clamping slot 123 and further the foot stand 500 isdisassembled from the airframe 100. During the installation process, theinsert 52 is inserted into the clamping slot 123 and then the fixingstand 51 is pushed upwards taking the insert 52 as the fulcrum, and whenthe fixing stand 51 is fitted into the accommodating groove 12, theinsertion end is embedded into the hole 122 by the elastic component 55,thus complete the installation.

In an embodiment, the fixing stand 51 is provided with a fixing groove511, and the insert 52 is configured to be a clamped piece extending outof the fixing groove 511. The fixing stand 51 is provided with aposition limiting groove 512 configured to limit an up-down movement ofthe pushrod 54, thus limiting and positioning the movement of thepushrod 54.

As shown in FIG. 10, in an embodiment, the plug pin 53 is provided witha stop piece 531 and the pushrod 54 is fitted over the plug pin 53 andlocated above the stop piece 531, thus pushing the plug pin 53 to movedownwards by means of the pushrod 54.

In other words, for the fast assembly and disassembly structure of thefoot stand 500 of the rotorcraft 1000 according to the presentdisclosure, the accommodating groove 12 having a downward opening isdisposed in the bottom wall of the airframe 100, and the fixing stand 51is fixedly connected to a top end of the foot stand 500. The top wall121 of the accommodating groove 12 is provided with the hole 122, andone side wall of the accommodating groove 12 is provided with theclamping slot 123. The fixing stand 51 has a shape corresponding withthat of the accommodating groove 12 and is accommodated into theaccommodating groove 12. One side of the fixing stand 51 is providedwith the clamped piece, and the clamped piece is inserted into theclamping slot 123 when the fixing stand 51 is accommodated in theaccommodating groove 12. The fixing stand 51 can be a hollow structure,and the plug pin 53 capable of moving upward and downward is disposedtherein, the extension direction of the plug pin 53 is coincident withthe height direction thereof, an upper end portion of the plug pin 53extends through the upper surface of the fixing stand 51, and theexposed portion forms the insertion end matching the hole 122 andinserted into the hole 122. A spring is fitted over the plug pin 53 andused to provide the elastic stress to push and press the plug pin 53upwards so that the insertion end on the top of the plug pin 53 isinserted into the hole 122. Specifically, the spring may be clampedbetween the bottom of the fixing stand 51 and the plug pin 53, orbetween the foot stand 500 and the plug pin 53, as long as a lowerportion of the spring is supported and an upper portion of the springpresses and pushes the plug pin 53. Certainly, in order to ensure theupper portion of the spring to press and push the plug pin 53 upwards,the plug pin 53 may be provided with the stop piece 531 pushing andpressing the upper portion of the spring, that is, the spring is limitedbetween the stop piece 531 and the bottom of the fixing stand 51 orbetween the stop piece 531 and the foot stand 500. It should be notedthat, the spring which provides the elastic stress for pushing the plugpin 53 may be other elastic components such as an elastic rubber block.The plug pin 53 is further connected with the pushrod 54, and thepushrod 54 leads the plug pin 53 to move downwards when presseddownwards, which can make the insertion end on the top of the plug pin53 separated from the hole 122. Specifically, an inside end of thepushrod 54 is fitted over the plug pin 53 and located on the stop piece531, and an outside end of the pushrod 54 passes through the positionlimiting groove 512 disposed in the fixing stand 51 and extends out ofthe fixing stand 51. The position limiting groove 512 is used to limitthe up-down movement of the pushrod 54 and guide the up-down movement ofthe pushrod 54.

When the fast assembly and disassembly structure in the presentdisclosure is disassembled, the outside end of the pushrod 54 is pusheddownwards, and the pushrod 54 leads the plug pin 53 to move downwards,the insertion end on the top of the plug pin 53 is separated from thehole 122, the foot stand 500 rotates taking the clamped piece as thefulcrum and makes the fixing stand 51 separated from the accommodatinggroove 12, thus detaching the foot stand 500 from the airframe 100quickly. During the installation, the clamped piece is inserted into theclamping slot 123, and the foot stand 500 is rotated taking the clampedpiece as the fulcrum, and when the upper surface of the fixing stand 51is attached to the top wall 121 of the accommodating groove 12, theinsertion end of the top of the plug pin 53 is inserted into the hole122, the plug pin 53 is engaged with the hole 122 under a function ofthe elastic stress of the spring, thus fixing the foot stand 500 to thebottom of the airframe 100.

The clamped piece mentioned above may be formed integrally with orseparately from the fixing stand 51, specifically, the fixing stand 51is provided with the fixing groove 511 and the clamped piece is fixed inthe fixing groove 511 and extends out of the fixing groove 511. Theclamped piece may be an aluminum sheet or other inserts 52 that can beembedded inside of the clamping slot 123.

The foot stand 500 is provided with a connecting stand 56, the spring islimited between the connecting stand 56 and the stop piece 531, an outercircumferential edge of the connecting stand 56 is provided with anexternal thread and the fixing stand 51 is provided with an internalthread matched with the external thread so that the fixing stand 51 isin threaded connection with the foot stand 500.

Reference throughout this specification to “an embodiment,” “someembodiments,” “illustrative embodiment”, “an example,” “a specificexample,” or “some examples,” means that a particular feature,structure, material, or characteristic described in connection with theembodiment or example is included in at least one embodiment or exampleof the present disclosure. In the present specification, theillustrative statement of the terms above is not necessarily referringto the same embodiment or example. Furthermore, the particular features,structures, materials, or characteristics may be combined in anysuitable manner in one or more embodiments or examples.

Although embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges, alternatives, variation and modifications can be made in theembodiments within the scope the present disclosure, and the scope ofthe present disclosure is limited by the claims and its equivalents.

What is claimed is:
 1. A connecting structure for an arm and an airframeof a rotorcraft comprising: a fixed sleeve pipe configured to extend outfrom a circumferential edge of the airframe; an insertion headconfigured to be disposed to a first end of the arm and configured to beinserted into the fixed sleeve pipe, wherein the insertion head isprovided with a protrusion portion protruding from an outer surface ofthe arm, and an insertion groove is formed between the protrusionportion and the outer surface of the arm; a lock sleeve configured to befitted over the arm and having an insertion portion configured to beembedded into the insertion groove, wherein the insertion portion andthe protrusion portion are configured to be in threaded connection; anda lock nut configured to be fitted over the arm and configured for beingin threaded connection with the fixed sleeve pipe, wherein a second endof the lock nut has a tensing end configured for abutting against asecond end face of the protrusion portion.
 2. The connecting structureaccording to claim 1, wherein a fitting surface is formed at a first endof the protrusion portion, and a first seal ring is configured to beclamped between an outer end face of the fixed sleeve pipe and thefitting surface.
 3. The connecting structure according to claim 1,wherein the insertion head is provided with an extension portionextending outwards in a radial direction, the protrusion portion isformed by means of an edge of the extension portion extending towards asecond end of the arm, and the fitting surface is an end surface of theextension portion.
 4. The connecting structure according to claim 1,wherein a first external thread is formed on an outer surface of thefixed sleeve pipe, and the lock nut is in threaded connection with thefirst external thread.
 5. The connecting structure according to claim 1,wherein a second external thread, in threaded connection with an innersurface of the protrusion portion, is formed on an outer surface of theinsertion portion.
 6. The connecting structure according to claim 1,wherein a second seal ring is configured to be fitted over the locksleeve and is clamped between an outer surface of the lock sleeve and aninner surface of the second end of the lock nut.
 7. The connectingstructure according to claim 1, wherein the insertion head is configuredto be fitted over the first end of the arm in a detachable manner. 8.The connecting structure according to claim 1, wherein connection piecesconfigured to turn on a circuit are disposed in the fixed sleeve pipeand the insertion head respectively.
 9. The connecting structureaccording to claim 8, wherein the fixed sleeve pipe is provided with afemale plug therein and, the insertion head is provided with a male plugconfigured to be electrically inserted into the female plug.
 10. Theconnecting structure according to claim 8, wherein metal sheets aredisposed in the fixed sleeve pipe and the insertion head respectively.11. The connecting structure according to claim 1, wherein an outersurface of the insertion head is provided with a groove extending in anaxial direction of the insertion head, and an inner wall of the fixedsleeve pipe is provided with a boss embedded into the groove.
 12. Arotorcraft comprising an arm, an airframe and a connecting structure forthe arm and the airframe, wherein the connecting structure comprises: afixed sleeve pipe configured to extend out from a circumferential edgeof the airframe; an insertion head configured to be disposed to a firstend of the arm and configured to be inserted into the fixed sleeve pipe,wherein the insertion head is provided with a protrusion portionprotruding from an outer surface of the arm, and an insertion groove isformed between the protrusion portion and the outer surface of the arm;a lock sleeve configured to be fitted over the arm and having aninsertion portion configured to be embedded into the insertion groove,wherein the insertion portion and the protrusion portion are configuredto be in threaded connection; and a lock nut configured to be fittedover the arm and configured for being in threaded connection with thefixed sleeve pipe, wherein a second end of the lock nut has a tensingend configured for abutting against a second end face of the protrusionportion.
 13. The rotorcraft according to claim 12, wherein a surface ofthe arm is provided with a flange, and the flange is clamped between theextension portion and the insertion portion.
 14. The rotorcraftaccording to claim 12 comprising a plurality of arms, wherein groovesare provided in different positions in insertion heads of the pluralityof arms, fixed sleeve pipes corresponding to the plurality of arms areprovided with bosses corresponding to the grooves in differentpositions.
 15. The rotorcraft according to claim 13 comprising aplurality of arms, wherein grooves are provided in different positionsin insertion heads of the plurality of arms, fixed sleeve pipescorresponding to the plurality of arms are provided with bossescorresponding to the grooves in different positions.
 16. The rotorcraftaccording to claim 12, further comprising a position limiting structure,the airframe is designed to have an upper housing and an lower housingthe fixed sleeve pipe is pre-embedded in a semi-circular groove of thelower housing, and a degree of freedom of the fixed sleeve pipe along anaxial direction thereof is limited by means of the position limitingstructure.
 17. The rotorcraft according to claim 13, further comprisinga position limiting structure, the airframe is designed to have an upperhousing and an lower housing the fixed sleeve pipe is pre-embedded in asemi-circular groove of the lower housing, and a degree of freedom ofthe fixed sleeve pipe along an axial direction thereof is limited bymeans of the position limiting structure.
 18. The rotorcraft accordingto claim 14, further comprising a position limiting structure, theairframe is designed to have an upper housing and an lower housing thefixed sleeve pipe is pre-embedded in a semi-circular groove of the lowerhousing, and a degree of freedom of the fixed sleeve pipe along an axialdirection thereof is limited by means of the position limitingstructure.
 19. The rotorcraft according to claim 15, further comprisinga position limiting structure, the airframe is designed to have an upperhousing and an lower housing the fixed sleeve pipe is pre-embedded in asemi-circular groove of the lower housing, and a degree of freedom ofthe fixed sleeve pipe along an axial direction thereof is limited bymeans of the position limiting structure.